Refrigerator and defrosting method thereof

ABSTRACT

A refrigerator according to the present invention includes a compressor compressing a coolant, a condenser condensing the coolant compressed in the compressor, an expander through which the coolant condensed in the condenser passes, an evaporator evaporating the coolant expanded in the expander and cooling an inside of the refrigerator, a defroster defrosting the evaporator, a coolant adjusting valve adjusting the coolant flowing from the condenser to the evaporator, and a controller driving the compressor and turning on the defroster after closing the coolant adjusting valve. The refrigerator may minimize power consumed for defrosting and the defrosting time.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2012-0009655 filed on Jan. 31, 2012, the contents of which are herein incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a refrigerator and a defrosting method of the refrigerator, and particularly, to a refrigerator that may defrost an evaporator and a defrosting method of the refrigerator.

DISCUSSION OF THE RELATED ART

In general, a refrigerator is an apparatus that includes a compressor, a condenser, an expander, and an evaporator and leaves a storage compartment, such as a refrigerating compartment or a freezing compartment, at a low temperature by using a freezing cycle of a coolant.

The refrigerator performs a defrosting operation that defrosts the evaporator. Such a defrosting operation may be initiated when too much frost is created on the evaporator. The defrosting operation may heat the evaporator by using a heater provided nearby or may heat the evaporator by introducing a high-temperature coolant to the evaporator.

SUMMARY OF THE INVENTION

Conventional refrigerators perform the defrosting operation on the evaporator while the coolant remains in the evaporator, so that the defrosting takes long and consumes more power. An object of the present invention is to provide a refrigerator that may minimize time taken to perform defrosting and a defrosting method of the refrigerator.

To achieve the above object, a refrigerator according to the present invention includes a compressor compressing a coolant, a condenser condensing the coolant compressed in the compressor, an expander through which the coolant condensed in the condenser passes, an evaporator evaporating the coolant expanded in the expander and cooling an inside of the refrigerator, a defroster defrosting the evaporator, a coolant adjusting valve adjusting the coolant flowing from the condenser to the evaporator, and a controller driving the compressor and turning on the defroster after closing the coolant adjusting valve.

The refrigerator may further include an evaporator fan blowing in-refrigerator air to the evaporator, wherein the controller may drive the evaporator fan while the compressor is driven and the coolant adjusting valve is closed.

The controller may turn on the defroster when a preset time passes after the compressor is stopped.

The controller may stop the compressor when a preset pump-down time passes after the coolant adjusting valve is closed.

The refrigerator may further include an evaporator fan blowing in-refrigerator air to the evaporator, wherein the controller may drive the evaporator fan while the compressor is driven, and the coolant adjusting valve is closed, and may additionally drive the evaporator fan during the preset time.

The controller may open the coolant adjusting valve while driving the compressor to cool the inside of the refrigerator.

A defrosting method of a refrigerator according to the present invention includes a pump-down step of driving a compressor and preventing a coolant from flowing to an evaporator and a defrosting step of defrosting the evaporator after the pump-down step.

A defrosting method of a refrigerator according to the present invention includes an in-refrigerator cooling step of cooling an inside of the refrigerator by driving a compressor, a pump-down step of driving the compressor and preventing a coolant from flowing to an evaporator after the in-refrigerator cooling step, and a defrosting step of defrosting the evaporator after the pump-down step.

The in-refrigerator cooling step may be performed longer than the pump-down step.

The pump-down step may close a coolant adjusting valve provided between a condenser and the evaporator.

The defrosting method may further include a coolant adjusting valve open step of opening the coolant adjusting valve after the defrosting step.

The pump-down step may stop the compressor after driving the compressor during a preset pump-down time.

The pump-down step may drive an evaporator fan that blows in-refrigerator air to the evaporator.

The defrosting method may further include an evaporator fan additional driving step of additionally driving the evaporator fan during a preset time after the pump-down step, wherein the defrosting step may be performed after the evaporator fan additional driving step.

The evaporator fan additional driving step may be performed shorter than the pump-down step.

The present invention defrosts the evaporator with the amount of coolant left in the evaporator, and thus, defrosting time and power consumed for defrosting may be minimized.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the present invention will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a view illustrating a configuration of a refrigerator according to a first embodiment of the present invention;

FIG. 2 is a control block diagram of the refrigerator according to the first embodiment of the present invention;

FIG. 3 is a flowchart illustrating a defrosting method according to a first embodiment of the present invention;

FIG. 4 is a view illustrating the defrosting method according to the first embodiment of the present invention;

FIG. 5 is a flowchart illustrating a defrosting method of a refrigerator according to a second embodiment of the present invention;

FIG. 6 is a view illustrating the defrosting method of the refrigerator according to the second embodiment of the present invention;

FIG. 7 is a flowchart illustrating a defrosting method of a refrigerator according to a third embodiment of the present invention; and

FIG. 8 is a view illustrating the defrosting method of the refrigerator according to the third embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a view illustrating a configuration of a refrigerator according to a first embodiment of the present invention, and FIG. 2 is a control block diagram of the refrigerator according to the first embodiment of the present invention.

Referring to FIGS. 1 and 2, the refrigerator may include a compressor 2 that compresses a coolant, a condenser 4 that condenses the coolant compressed by the compressor 2, an expander 6 through which the coolant condensed by the condenser 4 passes, an evaporator 8 that evaporates the coolant expanded by the expander 6 and freezes the inside of the refrigerator, a defroster 10 that defrosts the evaporator 8, and a coolant adjusting valve 12 provided between the condenser 4 and the evaporator 8.

The refrigerator may include a storage compartment, such as a refrigerating compartment and a freezing compartment. The refrigerator may include a mechanical compartment in which the compressor 2 may be provided. The refrigerator may include an outer casing that forms its outer appearance, an inner casing provided in the outer casing and including the storage compartment, and a door that opens and closes the storage compartment. The inner casing may be open at a surface, and the storage compartment may be provided in the inner casing. The refrigerator may include a partitioning plate that partitions the inside of the inner casing into the storage compartment and a heat exchanging compartment. The partitioning plate may include through holes that enable air in the refrigerator to be circulated between the storage compartment and the heat exchanging compartment.

The compressor 2 may compress the coolant evaporated by the evaporator 8 and may discharge the compressed coolant. The compressor 2 may be connected to the condenser 4 via a compressor-condenser connecting path 3. The coolant compressed by the compressor 2 may be guided to the condenser 4 through the compressor-condenser connecting path 3. The compressor 2 may be provided in the mechanical compartment provided in the refrigerator.

The condenser 4 may condense the coolant compressed by the compressor 2. The condenser 4 may be connected to the expander 6 via a condenser-expander connecting path 5. The coolant condensed by the condenser 4 may be guided to the expander 6 through the condenser-expander connecting path 5. The condenser 4 may be provided in the mechanical compartment of the refrigerator or may be provided to be exposed to the outside of the refrigerator.

The expander 6 may expand the coolant condensed by the condenser 4. The expander 6 may include a capillary tube or an electronic expansion valve, such as EEV or LEV. The expander 6 may be connected to the evaporator 8 via an expander-evaporator connecting path 7. The coolant expanded by the expander 6 may be guided to the evaporator 8 through the expander-evaporator connecting path 7.

The evaporator 8 performs heat exchange between the coolant expanded by the expander 6 and the inside of the refrigerator to thereby evaporate the coolant. The evaporator 8 may be connected to the compressor 2 via an evaporator-compressor connecting path 9. The coolant evaporated by the evaporator 8 may be introduced into the compressor 2 through the evaporator-compressor connecting path 9. The evaporator 8 may be provided at an outer wall of the inner casing or at the inside of the inner casing. The refrigerator may be a direct cooling type refrigerator in which the inner casing is cooled by the evaporator 8 and the storage compartment is cooled by conduction and free convection of air in the refrigerator. The refrigerator may be an indirect cooling type refrigerator in which the evaporator 8 is provided at a position other than the storage compartment and air in the refrigerator is forcedly circulated between the storage compartment and the evaporator 8 to thereby cool the storage compartment. When configured as an indirect cooling type refrigerator, the refrigerator may further include an evaporator fan 14 that blows air in the refrigerator to the evaporator 8.

A single evaporator 8 may cool both the refrigerating compartment and the freezing compartment. The evaporator 8 may include a freezing compartment evaporator and a refrigerating compartment evaporator that are connected in parallel with a coolant path. The freezing compartment evaporator may cool the freezing compartment, and the refrigerating compartment evaporator may cool the refrigerating compartment.

The defroster 10 is a mechanism that removes frost from the evaporator 8 by heating the evaporator 8. The defroster 10 includes a heater that generates heat when applied with a current and supplies the heat to the evaporator 8. The defroster 10 may include a path switching valve that shifts circulation of the coolant in the order of the compressor 2, the evaporator 8, the expander 6, the condenser 4, and the compressor 2. The defroster 10 may include a hot gas defrosting path that introduces part of the high-pressure, high-temperature coolant compressed by the compressor 2 to the evaporator 8.

Hereinafter, the defroster 10 is described as including a heater.

The coolant adjusting valve 12 may stop the coolant from flowing into the evaporator 8. The coolant adjusting valve 12 may be provided to adjust the coolant flowing from the condenser 4 to the evaporator 8. The coolant adjusting valve 12 may be provided at the condenser-expander connecting path 5 and may prevent the coolant condensed by the condenser 4 from flowing to the expander 6 and the evaporator 8. The coolant adjusting valve 12 may be provided at the expander-evaporator connecting path 7 and may prevent the coolant expanded by the expander 6 from flowing to the evaporator 8. While the compressor 2 compresses and discharges the introduced coolant, the coolant adjusting valve 12 may stop the coolant from flowing to the evaporator 8, and in such case, the refrigerator may remain in the ‘pump-down’ state in which the coolant from the evaporator 8 is collected in the condenser 4. That is, while the coolant is prevented from flowing into the evaporator 8, the compressor 2 may suck, compress, and then discharge the coolant, and the coolant may be gathered to a region between the coolant adjusting valve 12 and the condenser 4 and to the condenser 4 and the compressor 2. The refrigerator may further include a liquid receiver between the coolant adjusting valve 12 and the condenser 4 or between the condenser 4 and the compressor 2. When the refrigerator is in the pump-down state, the coolant may be collected in the liquid receiver. The coolant adjusting valve 12 may be constituted as a solenoid valve that operates on/off. The coolant adjusting valve 12 may be constituted as an electronic expanding valve, such as EEV or LEV, which may adjust the degree of opening.

The refrigerator may include the expander 6 and the coolant adjusting valve 12 separately from each other.

In the refrigerator, a single electronic expanding valve, such as EEV or LEV, may serve as both the expander 6 and the coolant adjusting valve 12. When making the coolant flow to the evaporator 8 to reduce the temperature of the storage compartment, the refrigerator may enable the electronic expanding valve, such as EEV or LEV, to be adjusted to the degree of opening in which the coolant is expanded. The coolant condensed by the condenser 4 may be expanded while passing through the electronic expanding valve, such as EEV or LEV, and may then flow to the evaporator 8. When the refrigerator shifts to the pump-down state so as to defrost the evaporator 8, the electronic expanding valve, such as EEV or LEV, may be closed to stop the coolant from flowing to the evaporator 8.

Hereinafter, the coolant adjusting valve 12 is described as provided separately from the expander 6.

When open, the coolant adjusting valve 12 may enable the coolant condensed by the condenser 4 to flow to the expander 6 or may enable the coolant expanded by the expander 6 to flow to the evaporator 8. When closed, the coolant adjusting valve 12 may inhibit the coolant, which has passed through the condenser 4, from flowing to the evaporator 8. The refrigerator may have a pump-down mode in which the compressor 2 remains in operation and the coolant adjusting valve 12 blocks the coolant from flowing to the evaporator 8.

The refrigerator may perform a defrosting operation that defrosts the evaporator 8 using the defroster 10. After performing a cooling operation that cools the storage compartment, the refrigerator may initiate the defrosting operation. The cooling operation and the defrosting operation may be alternately and repeatedly performed. During the cooling operation, the compressor 2 and the evaporator fan 14 may be driven. The refrigerator may periodically perform the defrosting operation between cooling operations. When a predetermined defrosting condition is met, the refrigerator may initiate the defrosting operation. The defrosting condition may be a condition in which the operation integration time of the compressor 2 reaches a preset integration time. The defrosting condition may be a condition in which the continuous driving time of the evaporator fan 14 reaches a preset driving time.

The refrigerator may turn on the defroster 10 while the coolant remains in the evaporator 8, and in such case, the coolant remaining in the evaporator 8 causes the time of defrosting by the defroster 10 to increase. On the contrary, when the refrigerator turns on the defroster 10 while no or a minimized amount of coolant is left in the evaporator 8, the time of defrosting by the defroster 10 decreases. The refrigerator may empty the coolant out of the evaporator 8 by operating in the pump-down mode when the defrosting operation is conducted, and after operating in the pump-down mode, may turn on the defroster 10 to perform a defrosting mode in which the evaporator 8 is defrosted.

The refrigerator may perform a precool mode for previously reducing the in-refrigerator temperature before performing the pump-down mode in consideration of an increase in the in-refrigerator temperature that occurs when the defroster 10 turns on. In the precool mode, the compressor 2 and the evaporator fan 14 may be driven so that the in-refrigerator temperature is decreased to a preset temperature or less.

Without performing the precool mode, the refrigerator may initiate the defrosting mode after performing the pump-down mode. The refrigerator may perform the pump-down mode after the precool mode and may perform the defrosting mode after the pump-down mode.

The refrigerator may include a controller 20 that controls the compressor 2, the defroster 10, and the coolant adjusting valve 12. The controller 20 may control the evaporator fan 14.

The refrigerator may include an input unit 22 that may input a desired temperature of the storage compartment or a defrosting command. The refrigerator may include an evaporator temperature sensor 24 that senses the temperature of the evaporator 8. The refrigerator may include a storage compartment temperature sensor 26 that senses the temperature of the storage compartment.

The controller 20 may control the compressor 2, the defroster 10, the coolant adjusting valve 12, and the evaporator fan 14 according to an input of the input unit 22, a sensing result of the evaporator temperature sensor 24, and a sensing result of the storage compartment temperature sensor 26.

When performing the defrosting mode after the pump-down mode, the controller 20 may drive the compressor 2 and may close the coolant adjusting valve 12, and after the coolant adjusting valve 12 is closed, may turn on the defroster 10.

The controller 20 may drive the evaporator fan 14 while the coolant adjusting valve 12 remains closed and the compressor 2 is driven. In the pump-down mode, if the evaporator fan 14 is driven, the coolant in the evaporator 8 may rapidly exchange heat with the in-refrigerator air, and the time taken for the entire coolant to travel from the evaporator 8 to a region other than the evaporator 8 decreases. In contrast, in the pump-down mode, unless the evaporator fan 14 is driven, the coolant in the evaporator 8 fails to quickly perform heat exchange with the in-refrigerator air, so that the time that the whole coolant in the evaporator 8 moves to the outside of the evaporator 8 increases.

The controller 20 may stop the compressor 2 when the pump-down mode is terminated. The controller 20 may perform the pump-down mode during a preset pump-down time. The preset pump-down time may be determined depending on the capacity of the evaporator 8 or the amount of the coolant. In the preset time after the compressor 2 is stopped, the controller 20 may turn on the defroster 10. When the compressor 2 is stopped, the refrigerator may terminate the pump-down mode, and may turn on the defroster 10 a preset time after the pump-down mode is ended, rather than turning on the defroster 10 right after the pump-down mode stops.

During the preset time after the pump-down mode is ended, the controller 20 may drive the evaporator fan 14. If the evaporator fan 14 is driven during the preset time, the refrigerator may enable the evaporator 8 to continue to cool the inside of the refrigerator and may shorten the time of defrosting of the evaporator 8 which is performed after the preset time by increasing the temperature of the evaporator 8 with the in-refrigerator air.

If the preset time passes, the controller 20 may stop the evaporator fan 14 and may turn on the defroster 10. Upon the turn-on of the defroster 10, the evaporator 8 is heated with the amount of coolant in the evaporator 8 minimized, by the pump-down mode, and the evaporator 8 may be heated more rapidly.

In case the controller 20 performs the pump-down mode after the precool mode and the defrosting mode after the pump-down mode, the controller 20 may, in the precool mode, open the coolant adjusting valve 12 while driving the compressor 2 to thereby cool the inside of the refrigerator, may, in the precool mode, close the coolant adjusting valve 12 and then stop the compressor 2, and may turn on the defroster 10 in the defrosting mode after the compressor 2 stops. A pump-down preset time after the coolant adjusting valve 12 is closed, the controller 20 may stop the compressor 2. A preset time after the compressor 2 is stopped, the controller 20 may turn on the defroster 10. While the compressor 2 is driven, the controller 20 may drive the evaporator fan 14. During a preset time, the controller 20 may drive the evaporator fan 14.

In case the evaporator 8 includes a freezing compartment evaporator and a refrigerating compartment evaporator, the expander 6 may include a freezing compartment expander that decompresses the coolant flowing to the freezing compartment evaporator and a refrigerating compartment expander that decompresses the coolant flowing to the refrigerating compartment evaporator. The coolant adjusting valve 12 may include a freezing compartment coolant adjusting valve that adjusts the coolant flowing to the freezing compartment evaporator and a refrigerating compartment coolant adjusting valve that adjusts the coolant flowing to the refrigerating compartment evaporator. The defroster 10 may include a defroster for the freezing compartment evaporator that heats the freezing compartment evaporator and a defroster for the refrigerating compartment evaporator that heats the refrigerating compartment evaporator. The evaporator fan 14 may include a freezing compartment evaporator fan that circulates cold air to the freezing compartment evaporator and the freezing compartment and a refrigerating compartment evaporator fan that circulates the cold air to the refrigerating compartment evaporator and the refrigerating compartment.

In the case of including the freezing compartment evaporator and the refrigerating compartment evaporator, when a defrosting condition of the freezing compartment evaporator is met, the refrigerator may perform a freezing compartment evaporator defrosting operation that executes a pump-down mode which drives the compressor 2 and closes the freezing compartment coolant adjusting valve and a defrosting mode when the defroster for the freezing compartment evaporator is turned on after the pump-down mode. In the case of including the freezing compartment evaporator and the refrigerating compartment evaporator, when a defrosting condition of the refrigerating compartment evaporator is met, the refrigerator may perform a freezing compartment evaporator defrosting operation that executes a pump-down mode which drives the compressor 2 and closes the refrigerating compartment coolant adjusting valve and a defrosting mode when the defroster for the refrigerating compartment evaporator is turned on after the pump-down mode. The refrigerator may sequentially perform the freezing compartment evaporator defrosting operation and the freezing compartment evaporator defrosting operation and independently from each other.

FIG. 3 is a flowchart illustrating a defrosting method according to a first embodiment of the present invention, and FIG. 4 is a view illustrating the defrosting method according to the first embodiment of the present invention.

The defrosting method of the refrigerator according to the embodiment includes pump-down steps S1, S2, and S3 and a defrosting step S4.

In the pump-down steps S1, S2, and S3, the compressor 2 is driven, and the coolant is prevented from flowing to the evaporator 8. In the pump-down steps S1, S2, and S3, the compressor 2 may be driven, and the coolant adjusting valve 12 provided between the condenser 4 and the evaporator 8 may be closed (S1). When the compressor 2 is driven, and the coolant adjusting valve 12 is closed, the coolant does not flow to the evaporator 8 and the coolant in the evaporator 8 is introduced in the compressor 2 and discharged by the compressor 2, and then flows to the condenser 4. The coolant in the evaporator 8 may be collected to the condenser 4.

In the pump-down steps S1, S2, and S3, the evaporator fan 14 that blows in-refrigerator air to the evaporator 8 (S1). When the evaporator fan 14 is driven while the compressor 2 is driven and the coolant adjusting valve 12 is closed, the evaporator 8 performs heat exchange with the in-refrigerator air blown by the evaporator fan 14, and the coolant in the evaporator 8 may be evaporated more quickly than when the evaporator fan 14 remains stopped, and the time during which the coolant is not left in the evaporator 8 may decrease. The pump-down steps S1, S2, and S3 may be periodically initiated. The pump-down steps S1, S2, and S3 may be initiated when the operation integration time of the compressor 2 reaches a preset integration time. The pump-down steps S1, S2, and S3 may be performed during a preset pump-down time. In the pump-down steps S1, S2, and S3, the compressor 2 may be stopped the preset pump-down time after the coolant adjusting valve 12 is closed. And, the evaporator fan 14 may be stopped (S2)(S3).

In the defrosting step S4, the evaporator 8 is defrosted after the pump-down step S1. In the defrosting step S4, the defroster 10 may be turned on, and the evaporator 8 may be heated by the defroster 10 with the coolant emptied in the evaporator 8 emptied. The evaporator 8 may be heated more rapidly than when the coolant remains in the evaporator 8. The defrosting step S4 may be performed during a preset defrost time, and the preset defrost time after the defroster 10 is turned on, the defrosting step S4 may be complete. The defrosting step S4 may be complete when the temperature of the evaporator 8 rises up to a preset defrost complete temperature after the defroster 10 is turned on. In the defrosting step S4, the defroster 10 may be turned off upon completion of the defrost.

The defrosting method of the refrigerator may further include a coolant adjusting valve opening step S5 in which, after the defrosting step S4, the coolant adjusting valve 12 is open. If the coolant adjusting valve 12 is open after the defrosting step S4, the cooling cycle leaves the coolant of the condenser 4 able to flow to the evaporator 8, and when the compressor 2 is afterward driven, the refrigerator may cool the inside of the evaporator 8.

FIG. 5 is a flowchart illustrating a defrosting method of a refrigerator according to a second embodiment of the present invention, and FIG. 6 is a view illustrating the defrosting method of the refrigerator according to the second embodiment of the present invention.

The defrosting method according to this embodiment may include pump-down steps S11, S12, and S13, evaporator fan additional driving steps S14 and S15, and a defrosting step S16.

Like in the pump-down steps S1, S2, and S3 according to the first embodiment, in the pump-down steps S11, S12, and S13, the compressor 2 is driven, and coolant is prevented from flowing to the evaporator 8. In the pump-down steps S11, S12, and S13, the compressor 2 may be driven and the coolant adjusting valve 12 may be closed, and the evaporator fan 14 may be driven (S11). The pump-down steps S11, S12, and S13 may be performed during a preset pump-down time. In the pump-down steps S11, S12, and S13, if the preset pump-down time passes after the coolant adjusting valve 12 is closed, the compressor 2 may be stopped (S12)(S13). Upon completion of the pump-down steps S11, S12, and S13, only the compressor 2 may be stopped without stopping the evaporator fan 14.

In the evaporator fan additional driving steps S14 and S15, the evaporator fan 14 is driven during a preset time after the pump-down steps S11, S12, and S13. In this embodiment, upon completion of the pump-down steps S11, S12, and S13, the evaporator fan 14 is not stopped while the evaporator fan 14 may be continuously driven during the evaporator fan additional driving steps S14 and S15. That is, the evaporator fan 14 continues to be driven during the preset time of the evaporator fan additional driving steps S14 and S15 and the preset pump-down time of the pump-down steps S11, S12, and S13, and may be stopped before the defrosting step S16. The evaporator fan additional driving steps S14 and S15 may be performed during a shorter time than that of the pump-down steps S11, S12, and S13.

The defrosting step S16 may be initiated after the evaporator fan additional driving steps S14 and S15. In the defrosting method of the refrigerator according to this embodiment, after the pump-down steps S11, S12, and S13 are performed, the evaporator fan additional driving steps S14 and S15 may be performed, and after the evaporator fan additional driving steps S14 and S15 are performed, the defrosting step S16 may be performed. The defrosting step S16 may be performed a preset time after the compressor 2 is stopped. In the defrosting step S16, like in the defrosting step S4 according to the first embodiment of the present invention, the defroster 10 may be turned on, and the evaporator 8 may be heated by the defroster 10 with the coolant emptied out of the inside of the evaporator 8. The defrosting step S16 may be performed during a preset defrosting time. The defrosting step S16 may be complete a preset defrosting time after the defroster 10 is turned on. The defrosting step S16 may be complete if the temperature of the evaporator 8 rises up to a preset defrosting complete temperature after the defroster 10 is turned on. The defrosting step S16 may turn off the defroster 10 upon completion of the defrosting.

The defrosting method of the refrigerator may further include a coolant adjusting valve open step S17 that opens the coolant adjusting valve 12 after the defrosting step S16. The refrigerator may cool the inside of the evaporator 8 after the coolant adjusting valve 12 is open.

FIG. 7 is a flowchart illustrating a defrosting method of a refrigerator according to a third embodiment of the present invention, and FIG. 8 is a view illustrating the defrosting method of the refrigerator according to the third embodiment of the present invention.

In this embodiment, the defrosting method of the refrigerator includes in-refrigerator cooling steps S21 and S22, pump-down steps S23, S24, and S25, and a defrosting step S28. In the defrosting method of the refrigerator according to this embodiment, after the pump-down steps S23, S24, and S25, like in the second embodiment of the present invention, evaporator fan additional driving steps S26 and S27 may be performed, and after the evaporator fan additional driving steps S26 and S27, the defrosting step S28 may be performed.

In the in-refrigerator cooling steps S21 and S22, the compressor 2 is driven to cool the inside of the refrigerator. The in-refrigerator cooling steps S21 and S22 are precool steps that previously lower the in-refrigerator temperature before the pump-down steps S23, S24, and S25 in consideration of an increase in the in-refrigerator temperature that may occur upon the defrosting step S28. In the in-refrigerator cooling steps S21 and S22, the compressor 2 and the evaporator fan 14 may be driven so that the in-refrigerator temperature decreases to a preset precool temperature or less. The in-refrigerator cooling steps S21 and S22 may be periodically initiated. The in-refrigerator cooling steps S21 and S22 may be initiated when an operation integration time of the compressor 2 reaches a preset integration time The in-refrigerator cooling steps S21 and S22 may be initiated when a continuous driving time of the evaporator fan 14 reaches a preset driving time. The in-refrigerator cooling steps S21 and S22 may be performed during a preset cooling time. The in-refrigerator cooling steps S21 and S22 may be performed longer than the pump-down steps S23, S24, and S25. The preset cooling time may be set to be longer than the preset pump-down time of the pump-down steps S23, S24, and S25. The in-refrigerator cooling steps S21 and S22 may be complete when a preset cooling time passes after the compressor 2 and the evaporator fan 14 are driven.

In the pump-down steps S23, S24, and S25, after the in-refrigerator cooling steps S21 and S22, the compressor 2 is driven and the coolant is prevented from flowing to the evaporator 8. In the pump-down steps S23, S24, and S25, like in the pump-down steps S11, S12, and S13 according to the second embodiment of the present invention, the coolant adjusting valve 12 may be closed (S23). In the pump-down steps S23, S24, and S25, the compressor 2, which has been driven in the in-refrigerator cooling steps S21 and S22, may be continuously driven, and the evaporator fan 14 may be continuously driven. The pump-down steps S23, S24, and S25 may be performed during a preset pump-down time. In the pump-down steps S23, S24, and S25, if the preset pump-down time passes after the coolant adjusting valve 12 is closed, the compressor 2 may be stopped (S24)(S25). In the pump-down steps S23, S24, and S25, only the compressor 2 may be stopped without stopping the evaporator fan 14.

The evaporator fan additional driving steps S26 and S27 may be performed together with the evaporator fan additional driving steps S14 and S15 according to the second embodiment of the present invention. In the evaporator fan additional driving steps S26 and S27, the evaporator fan 14 may be driven during a preset time after the pump-down steps S23, S24, and S25. The evaporator fan 14 may continue to be driven during the evaporator fan additional driving steps S26 and S27 without pause upon completion of the pump-down steps S23, S24, and S25.

In the defrosting step S28, the evaporator 8 may be defrosted after the pump-down steps S23, S24, and S25. The defrosting step S28 may be performed after the evaporator fan additional driving steps S26 and S27. That is, in the defrosting method of the refrigerator according to this embodiment, after the pump-down steps S23, S24, and S25 are performed, the evaporator fan additional driving steps S26 and S27 may be performed, and after the evaporator fan additional driving steps S26 and S27 are performed, the defrosting step S28 may be performed. The defrosting step S28 may be performed a preset time after the compressor 2 is stopped. In the defrosting step S28, like in the defrosting step S16 according to the second embodiment of the present invention, the defroster 10 may be turned on. The defrosting step S28 may be performed during a preset defrosting time, and may be complete when a preset defrosting time passes after the defroster 10 is turned on. The defrosting step S28 may be complete when the temperature of the evaporator 8 rises up to a preset defrost complete temperature after the defroster 10 is turned on. In the defrosting step S28, the defroster 10 may be turned off upon completion of the defrosting.

The defrosting method of the refrigerator may further include a coolant adjusting valve open step S29 that, after the defrosting step S28, opens the coolant adjusting valve 12. In the refrigerator, the evaporator 8 may cool the inside of the refrigerator after the coolant adjusting valve 12 is open. 

What is claimed is:
 1. A refrigerator comprising: a compressor compressing a coolant; a condenser condensing the coolant compressed in the compressor; an expander through which the coolant condensed in the condenser passes; an evaporator evaporating the coolant expanded in the expander and cooling an inside of the refrigerator; a defroster defrosting the evaporator; a coolant adjusting valve adjusting the coolant flowing from the condenser to the evaporator; and a controller driving the compressor and turning on the defroster after closing the coolant adjusting valve.
 2. The refrigerator of claim 1, further comprising an evaporator fan blowing in-refrigerator air to the evaporator, wherein the controller drives the evaporator fan while the compressor is driven and the coolant adjusting valve is closed.
 3. The refrigerator of claim 1, wherein the controller turns on the defroster when a preset time passes after the compressor is stopped.
 4. The refrigerator of claim 3, wherein the controller stops the compressor when a preset pump-down time passes after the coolant adjusting valve is closed.
 5. The refrigerator of claim 3, further comprising an evaporator fan blowing in-refrigerator air to the evaporator, wherein the controller drives the evaporator fan while the compressor is driven, and the coolant adjusting valve is closed, and additionally drives the evaporator fan during the preset time.
 6. The refrigerator of claim 1, wherein the controller opens the coolant adjusting valve while driving the compressor to cool the inside of the refrigerator.
 7. A defrosting method of a refrigerator, the defrosting method comprising: a pump-down step of driving a compressor and preventing a coolant from flowing to an evaporator; and a defrosting step of defrosting the evaporator after the pump-down step.
 8. The defrosting method of claim 7, wherein the pump-down step closes a coolant adjusting valve provided between a condenser and the evaporator.
 9. The defrosting method of claim 8, further comprising a coolant adjusting valve open step of opening the coolant adjusting valve after the defrosting step.
 10. The defrosting method of claim 7, wherein the pump-down step stops the compressor after driving the compressor during a preset pump-down time.
 11. The defrosting method of claim 7, wherein the pump-down step drives an evaporator fan that blows in-refrigerator air to the evaporator.
 12. The defrosting method of claim 11, further comprising an evaporator fan additional driving step of additionally driving the evaporator fan during a preset time after the pump-down step, wherein the defrosting step is performed after the evaporator fan additional driving step.
 13. The defrosting method of claim 12, wherein the evaporator fan additional driving step is performed shorter than the pump-down step.
 14. A defrosting method of a refrigerator, the defrosting method comprising: an in-refrigerator cooling step of cooling an inside of the refrigerator by driving a compressor; a pump-down step of driving the compressor and preventing a coolant from flowing to an evaporator after the in-refrigerator cooling step; and a defrosting step of defrosting the evaporator after the pump-down step.
 15. The defrosting method of claim 14, wherein the in-refrigerator cooling step is performed longer than the pump-down step.
 16. The defrosting method of claim 14, wherein the pump-down step closes a coolant adjusting valve provided between a condenser and the evaporator.
 17. The defrosting method of claim 16, further comprising a coolant adjusting valve open step of opening the coolant adjusting valve after the defrosting step.
 18. The defrosting method of claim 14, wherein the pump-down step stops the compressor after driving the compressor during a preset pump-down time.
 19. The defrosting method of claim 14, wherein the pump-down step drives an evaporator fan that blows in-refrigerator air to the evaporator.
 20. The defrosting method of claim 19, further comprising an evaporator fan additional driving step of additionally driving the evaporator fan during a preset time after the pump-down step, wherein the defrosting step is performed after the evaporator fan additional driving step.
 21. The defrosting method of claim 12, wherein the evaporator fan additional driving step is performed shorter than the pump-down step. 